Battery tester for electric vehicle

ABSTRACT

Testing or diagnostics are performed on an electric vehicle. The vehicle is operated and current flow through a system of the vehicle is monitored. A voltage related to the system is also monitored. Diagnostics are provided based upon the monitored voltage and the monitored current.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims the benefit of U.S.provisional patent application Ser. No. 60/950,182, filed Jul. 17, 2007,and U.S. provisional patent application Ser. No. 60/970,319, filed Sep.6, 2007, the contents of which are hereby incorporated by reference intheir entirety.

BACKGROUND OF THE INVENTION

The present invention relates to test equipment for electric tovehicles. More specifically, the present invention relates to a testerfor testing electrical systems of an electric vehicle.

Various battery testing techniques and related technologies have beenpioneered by Midtronics Inc. and Dr. Keith S. Champlin, including forexample: U.S. Pat. No. 3,873,911, issued Mar. 25, 1975, to Champlin;U.S. Pat. No. 3,909,708, issued Sep. 30, 1975, to Champlin; U.S. Pat.No. 4,816,768, issued Mar. 28, 1989, to Champlin; U.S. Pat. No.4,825,170, issued Apr. 25, 1989, to Champlin; U.S. Pat. No. 4,881,038,issued Nov. 14, 1989, to Champlin; U.S. Pat. No. 4,912,416, issued Mar.27, 1990, to Champlin; U.S. Pat. No. 5,140,269, issued Aug. 18, 1992, toChamplin; U.S. Pat. No. 5,343,380, issued Aug. 30, 1994; U.S. Pat. No.5,572,136, issued Nov. 5, 1996; U.S. Pat. No. 5,574,355, issued Nov. 12,1996; U.S. Pat. No. 5,583,416, issued Dec. 10, 1996; U.S. Pat. No.5,585,728, issued Dec. 17, 1996; U.S. Pat. No. 5,589,757, issued Dec.31, 1996; U.S. Pat. No. 5,592,093, issued Jan. 7, 1997; U.S. Pat. No.5,598,098, issued Jan. 28, 1997; U.S. Pat. No. 5,656,920, issued Aug.12, 1997; U.S. Pat. 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No.09/780,146, filed Feb. 9, 2001, entitled STORAGE BATTERY WITH INTEGRALBATTERY TESTER; U.S. Ser. No. 09/756,638, filed Jan. 8, 2001, entitledMETHOD AND APPARATUS FOR DETERMINING BATTERY PROPERTIES FROM COMPLEXIMPEDANCE/ADMITTANCE; U.S. Ser. No. 09/862,783, filed May 21, 2001,entitled METHOD AND APPARATUS FOR TESTING CELLS AND BATTERIES EMBEDDEDIN SERIES/PARALLEL SYSTEMS; U.S. Ser. No. 09/880,473, filed Jun. 13,2001; entitled BATTERY TEST MODULE; U.S. Ser. No. 10/042,451, filed Jan.8, 2002, entitled BATTERY CHARGE CONTROL DEVICE; U.S. Ser. No.10/109,734, filed Mar. 28, 2002, entitled APPARATUS AND METHOD FORCOUNTERACTING SELF DISCHARGE IN A STORAGE BATTERY; U.S. Ser. No.10/112,998, filed Mar. 29, 2002, entitled BATTERY TESTER WITH BATTERYREPLACEMENT OUTPUT; U.S. Ser. No. 10/263,473, filed Oct. 2, 2002,entitled ELECTRONIC BATTERY TESTER WITH RELATIVE TEST OUTPUT; U.S. Ser.No. 10/310,385, filed Dec. 5, 2002, entitled BATTERY TEST MODULE; U.S.Ser. No. 10/462,323, filed Jun. 16, 2003, entitled ELECTRONIC BATTERYTESTER HAVING A USER INTERFACE TO CONFIGURE A PRINTER; U.S. Ser. No.10/653,342, filed Sep. 2, 2003, entitled ELECTRONIC BATTERY TESTERCONFIGURED TO PREDICT A LOAD TEST RESULT; U.S. Ser. No. 10/441,271,filed May 19, 2003, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No.09/653,963, filed Sep. 1, 2000, entitled SYSTEM AND METHOD FORCONTROLLING POWER GENERATION AND STORAGE; U.S. Ser. No. 10/174,110,filed Jun. 18, 2002, entitled DAYTIME RUNNING LIGHT CONTROL USING ANINTELLIGENT POWER MANAGEMENT SYSTEM; U.S. Ser. No. 10/258,441, filedApr. 9, 2003, entitled CURRENT MEASURING CIRCUIT SUITED FOR BATTERIES;U.S. Ser. No. 10/681,666, filed Oct. 8, 2003, entitled ELECTRONICBATTERY TESTER WITH PROBE LIGHT; U.S. Ser. No. 10/783,682, filed Feb.20, 2004, entitled REPLACEABLE CLAMP FOR ELECTRONIC BATTERY TESTER; U.S.Ser. No. 10/791,141, filed Mar. 2, 2004, entitled METHOD AND APPARATUSFOR AUDITING A BATTERY TEST; U.S. Ser. No. 10/867,385, filed Jun. 14,2004, entitled ENERGY MANAGEMENT SYSTEM FOR AUTOMOTIVE VEHICLE; U.S.Ser. No. 10/896,834, filed Jul. 22, 2004, entitled ELECTRONIC BATTERYTESTER; U.S. Ser. No. 10/958,821, filed Oct. 5, 2004, entitledIN-VEHICLE BATTERY MONITOR; U.S. Ser. No. 10/958,812, filed Oct. 5,2004, entitled SCAN TOOL FOR ELECTRONIC BATTERY TESTER; U.S. Ser. No.11/008,456, filed Dec. 9, 2004, entitled APPARATUS AND METHOD FORPREDICTING BATTERY CAPACITY AND FITNESS FOR SERVICE FROM A BATTERYDYNAMIC PARAMETER AND A RECOVERY VOLTAGE DIFFERENTIAL, U.S. Ser. No.60/587,232, filed Dec. 14, 2004, entitled CELLTRON ULTRA, U.S. Ser. No.11/018,785, filed Dec. 21, 2004, entitled WIRELESS BATTERY MONITOR; U.S.Ser. No. 60/653,537, filed Feb. 16, 2005, entitled CUSTOMER MANAGEDWARRANTY CODE; U.S. Ser. No. 11/063,247, filed Feb. 22, 2005, entitledELECTRONIC BATTERY TESTER OR CHARGER WITH DATABUS CONNECTION; U.S. Ser.No. 60/665,070, filed Mar. 24, 2005, entitled OHMMETER PROTECTIONCIRCUIT; U.S. Ser. No. 11/141,234, filed May 31, 2005, entitled BATTERYTESTER CAPABLE OF IDENTIFYING FAULTY BATTERY POST ADAPTERS; U.S. Ser.No. 11/143,828, filed Jun. 2, 2005, entitled BATTERY TEST MODULE; U.S.Ser. No. 11/146,608, filed Jun. 7, 2005, entitled SCAN TOOL FORELECTRONIC BATTERY TESTER; U.S. Ser. No. 60,694,199, filed Jun. 27,2005, entitled GEL BATTERY CONDUCTANCE COMPENSATION; U.S. Ser. No.11/178,550, filed Jul. 11, 2005, entitled WIRELESS BATTERYTESTER/CHARGER; U.S. Ser. No. 60/705,389, filed Aug. 4, 2005, entitledPORTABLE TOOL THEFT PREVENTION SYSTEM, U.S. Ser. No. 11/207,419, filedAug. 19, 2005, entitled SYSTEM FOR AUTOMATICALLY GATHERING BATTERYINFORMATION FOR USE DURING BATTERY TESTER/CHARGING, U.S. Ser. No.60/712,322, filed Aug. 29, 2005, entitled AUTOMOTIVE VEHICLE ELECTRICALSYSTEM DIAGNOSTIC DEVICE, U.S. Ser. No. 60/713,168, filed Aug. 31, 2005,entitled LOAD TESTER SIMULATION WITH DISCHARGE COMPENSATION, U.S. Ser.No. 60/731,881, filed Oct. 31, 2005, entitled PLUG-IN FEATURES FORBATTERY TESTERS; U.S. Ser. No. 60/731,887, filed Oct. 31, 2005, entitledAUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE; U.S. Ser. No.11/304,004, filed Dec. 14, 2005, entitled BATTERY TESTER THAT CALCULATESITS OWN REFERENCE VALUES; U.S. Ser. No. 60/751,853, filed Dec. 20, 2005,entitled BATTERY MONITORING SYSTEM; U.S. Ser. No. 11/304,004, filed Dec.14, 2005, entitled BATTERY TESTER WITH CALCULATES ITS OWN REFERENCEVALUES; U.S. Ser. No. 60/751,853, filed Dec. 20, 2005, entitled BATTERYMONITORING SYSTEM; U.S. Ser. No. 11/352,945, filed Feb. 13, 2006,entitled BATTERY TESTERS WITH SECONDARY FUNCTIONALITY; U.S. Ser. No.11/356,299, filed Feb. 16, 2006, entitled CENTRALLY MONITORED SALES OFSTORAGE BATTERIES; U.S. Ser. No. 11/356,443, filed Feb. 16, 2006,entitled ELECTRONIC BATTERY TESTER WITH NETWORK COMMUNICATION; U.S. Ser.No. 11/498,703, filed Aug. 3, 2006, entitled THEFT PREVENTION DEVICE FORAUTOMOTIVE VEHICLE SERVICE CENTERS; U.S. Ser. No. 11/507,157, filed Aug.21, 2006, entitled APPARATUS AND METHOD FOR SIMULATING A BATTERY TESTERWITH A FIXED RESISTANCE LOAD; U.S. Ser. No. 11/511,872, filed Aug. 29,2006, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE;U.S. Ser. No. 11/519,481, filed Sep. 12, 2006, entitled BROAD-BANDLOW-CONDUCTANCE CABLES FOR MAKING KELVIN CONNECTIONS TO ELECTROCHEMICALCELLS AND BATTERIES; U.S. Ser. No. 60/847,064, filed Sep. 25, 2006,entitled STATIONARY BATTERY MONITORING ALGORITHMS; U.S. Ser. No.11/638,771, filed Dec. 14, 2006, entitled BATTERY MONITORING SYSTEM;U.S. Ser. No. 11/641,594, filed Dec. 19, 2006, entitled METHOD ANDAPPARATUS FOR MEASURING A PARAMETER OF A VEHICLE ELECTRONIC SYSTEM; U.S.Ser. No. 11/711,356, filed Feb. 27, 2007, entitled BATTERY TESTER WITHPROMOTION FEATURE; U.S. Ser. No. 11/811,528, filed Jun. 11, 2007,entitled ALTERNATOR TESTER; U.S. Ser. No. 60/950,182, filed Jul. 17,2007, entitled BATTERY TESTER FOR HYBRID VEHICLE; U.S. Ser. No.60/973,879, filed Sep. 20, 2007, entitled ELECTRONIC BATTERY TESTER FORTESTING STATIONARY BATTERIES; U.S. Ser. No. 11/931,907, filed Oct. 31,2007, entitled BATTERY MAINTENANCE WITH PROBE LIGHT; U.S. Ser. No.60/992,798, filed Dec. 6, 2007,entitled STORAGE BATTERY AND BATTERYTESTER; U.S. Ser. No. 12/099,826, filed Apr. 9, 2008, entitled BATTERYRUN DOWN INDICATOR; U.S. Ser. No. 61/061,848, filed Jun. 16, 2008,entitled KELVIN CLAMP FOR ELECTRONICALLY COUPLING TO A BATTERY CONTACT;which are incorporated herein in their entirety.

Many electric vehicles use a battery or other electrical storage deviceto store energy for use in operating the electric vehicle. Some suchelectric vehicles use energy recovering (or “regeneration”) techniquesin which potentially waste energy is recovered and stored in the energystorage device. One example is recovery of energy from the brakingfunction. The energy in braking is recovered as electrical energy ratherthan being dissipated as excess heat. The energy storage device shouldbe able to sufficiently store the excess energy, as well as deliverenergy to the electrical motor of the electric vehicle. Due to theincreasing price of petroleum, hybrid systems are rapidly proliferating,and are outpacing the ability to test those systems. There is an ongoingneed to test the electrical systems of such electric vehicles.

SUMMARY OF THE INVENTION

Testing or diagnostics are performed on an electric vehicle. The vehicleis operated and current flow through a system of the vehicle ismonitored. A voltage related to the system is also monitored.Diagnostics are provided based upon the monitored voltage and themonitored current.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram showing a battery tester inaccordance with the present invention coupled to a electric vehicle.

FIG. 2 is a simplified block diagram showing steps in accordance withthe present invention.

FIG. 3 is a simplified block diagram which illustrates a test device inaccordance with the present invention.

FIG. 4 is a simplified block diagram showing one aspect of the presentinvention in which the test device couples to the databus of theelectric vehicle.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Electric vehicles are becoming increasingly popular as an alternative totraditional vehicles which are powered solely by an internal combustionengine. In a electric vehicle, a large battery or a group of batteries,or other energy storage device, is used to store electrical energy. Thestored electrical power is used by an electric motor to power theelectric vehicle.

In order to increase energy efficiency, some electric vehicles usevarious techniques to capture or otherwise recover waste energy. Thismay be referred to as “regeneration”. The recovered energy is typicallyreturned in the battery of the electric vehicle for storage andsubsequent use.

Various techniques are used to recover energy. For example, one commontechnique is to use the braking system of the electric vehicle toconvert vehicle motion into electricity for storage in the battery. Thisdiffers from a conventional braking system in which excess energy isvented into the atmosphere as heat.

As the battery of the electric vehicle ages, its ability to store energyalso degrades. However, this may not be apparent to the operator,particularly in a hybrid vehicle. One symptom of a failing battery isdecreased mileage of the electric vehicle because the battery is notable to effectively store or deliver energy. The health of a battery ina electric vehicle is an indication of how well the battery accepts acharge and delivers stored energy at high rates. To some extent, thisrelates to the amp hour capacity of the battery as well as the abilityof the battery to accept or deliver charge in a given time. This isrelated to how much recovered energy can be stored at one time for lateruse. For example, is the battery capable of storing energy from manybraking cycles for subsequent use, or only a few.

Typical battery testing techniques are difficult to implement in such aelectric vehicle. For example, it may be difficult or impossible toaccess the individual batteries or cell for testing. This may require agreat deal of labor. Further, there may be safety concerns related tothe relatively high voltages involved.

With the present invention, a current sensor is coupled to the batterypack of a electric vehicle of the type which includes an electric motorto move the electric vehicle. The current sensor can be placed in linewith the battery pack and arranged to measure current into and out ofthe pack. The total string voltage of the battery pack is also measured.A technician or other service personnel performs a battery test byoperating the electric vehicle through a number of braking andacceleration cycles. Data is collected and compared to baseline ornominal data which is representative of operation of a new electricvehicle. An output can be provided based upon the comparison. Forexample, the output can be an indication of how well the electricvehicle compares to new electric vehicle, for example as a percentage.

The current sensor can be placed in series with one of the batteryterminals using a shunt resistance or the like. Another example is aHall effect or other non intrusive sensor. Such a sensor is advantageousbecause it does not require the battery to be disconnected. In anotherexample, an adapter can be configured which can be inserted between thebattery pack and the electric vehicle such that the test device can becoupled to the battery.

The various sensors can be coupled at any convenient location, forexample, proximate the battery pack, under the hood, near the electricvehicle motor or other electronics. In such an application, a Halleffect sensor may be sufficient because of the relatively largemagnitudes of the current levels being monitored. Further, a Hall effectsensor may be easily “zeroed” because during installation there will beno current flowing. Voltage measurements may be made using directattachment, for example, to the high voltage pole of the battery. Thevoltage measurements may also be obtained through other techniques, forexample, through an OBDII interface used to read the voltage from theelectric vehicle computer system. This may be preferable when using awireless communication port.

During testing, the test device can provide instructions to an operatoras to how to operate the electric vehicle. Such instructions can beprovided, for example, through a wireless communication link to adevice, through a PDA-type device, through audible instructions, througha display of the vehicle, or through other techniques.

If the testing device couples to the OBDII system of the electricvehicle, additional information can be retrieved. For example,information related to the RPM of a motor, electric vehicle speed,braking information, etc. can be recovered. With this additionalinformation, the test device may be used to verify that the technicianhas performed the required operations. Of course, such operations shouldhave some flexibility in order to reflect safe driving conditions.

FIG. 1 is a simplified block diagram 10 of a electric vehicle 12 coupledto a test device 14. The test device is shown as being separate from theelectric vehicle and may be a portable or stationary device. However, insome configurations the test device 14 may be included in electricvehicle 12. Electric vehicle 12 is illustrated as including battery pack20, electric motor 22 and energy recovery device 24. As discussed, thebattery pack 20 is used to power the electric motor 22 while the energyrecover device 24 is used to recover energy during electric vehicleoperation. Test circuitry 14 couples to battery 20 and includes or iscoupled to voltage sensor 30, memory 32 and microprocessor 33. Further,test circuitry 14 includes or is coupled to a current sensor 34 arrangedto sensor current into and/or out of battery pack 20. Test circuitry 14provides an output through input/output (I/O) 35 as discussed aboverelated to the condition of the battery pack 20. The test circuitry 14includes a microprocessor 33 or the like which may include eitherinternal or external analog to digital converters configured to convertthe sensed voltage current levels to digital values. Microprocessor 33operates in accordance with instructions stored in memory and provide anoutput 35 which is related to the condition of the battery pack 20. FIG.1 also shows an optional internal combustion engine 40 which is used tosupplement the energy delivered by battery pack 20. The optional engine40 can be used to charge battery pack 20, and/or can be used tosupplement the electrical power available to motor 22 during times ofhigh acceleration or the like. Thus, engine 40 may include an electricgenerator 41.

FIG. 2 is a simplified block diagram showing steps in accordance withone example embodiment of the present invention. The block diagram ofFIG. 2 begins at start block 50 and controls past block 52 where theelectric vehicle is operated and data is collected. At block 54, nominaldata is recovered. For example, such nominal data can be stored inmemory 32 shown in FIG. 1. The nominal data can be related to a baselinecondition, for example, the condition of the battery in electric vehiclewhen they are new. At block 56, the collected data is compared to thenominal data and output is provided at block 58. The output can be, forexample, a relative output with respect to the current condition ofelectric vehicle in battery relative to a new electric vehicle orbattery. This may be in the form of, for example, a percentage or otherformat. At block 60, the process is terminated.

FIG. 3 is a simplified block diagram showing test device 14 in greaterdetail. Test device 14 is illustrated as including differentialamplifier 102 which couples to current sensor 34. A second differentialamplifier 98 couples to battery 20 and forms the voltage sensor 30. Thevoltage sensor 30 may be a part of, or may be separated from, the testdevice 14. The output from the amplifier 98 is provided through ananalog to digital converter 100 which couples microprocessor 33.Similarly, the output of amplifier 102 is converted into a digitalformat for microprocessor 33 using analog to digital converter 104. Theactual voltage and current sensors may be in accordance with anytechnique and is not limited to the techniques described herein. Asdiscussed below, the current and voltage sensors may be a part ofvehicle 12 and the test can retrieve their information over a databus ofthe vehicle.

Microprocessor 33 operates in accordance with instructions stored inmemory 32 and is configured to communicate with an operator through userI/O 110. An optional OBD interface, as illustrated at OBD I/O 112, isprovided. OBD I/O 112 is configured to couple to the OBD databus of theelectric vehicle 12. The user I/O 110 can be any type of user input andoutput including, for example, a button or keypad entry, a displayincluding a graphical display, an audio output including voice prompts,or other input or output techniques.

FIG. 4 is a simplified block diagram showing another aspect of thepresent invention. As discussed above, test device 14 couples to the onboard databus 130 of electric vehicle 12, for example through OBDconnector 132. Electric vehicle 12 is illustrated as including aplurality of systems identified as System A, B, C through System N.These systems can be any active or passive electrical component or setof components within the vehicle including a motor or motors of thevehicle, an energy recovery system such as a regenerative brakingsystem, a battery cell, a block of cells, a battery pack, vehicleelectronics such as audio systems, defrosters, wipers, adjustable seatmotors, set heaters, lights both internal and external, computersystems, electrical system associated with an electric or internalcombustion motor, charging systems, or others. Each of the systems A-Nis illustrated as having a current sensor 140A-140N, respectively and avoltage sensor 142A-142N, respectively. The multiple current sensors 140and voltage sensors 142 are provided for illustrative purposes only anda particular system within the vehicle may be have neither type ofsensor, may have a single sensor, or may have multiple sensors. Theoutputs from the current sensors 140 the voltage sensors 142 areprovided to the internal databus of the electric vehicle 130. Theelectric vehicle 12 may include additional sensors for sensing physicalproperties such as temperature, moisture content, fluid levels,pressures, speed or rate of rotation of motors, flow rate, whether aswitch is opened or closed, etc. These sensors are illustrated in FIG. 4as sensor A, B through sensor N and are also coupled to the databus 130of electric vehicle 12. The sensors A, B, . . . N may be associated withany of the above discussed systems A-N, or with other components oraspects of the electric vehicle 12. For example, a particular sensor mayprovide a temperature reading of a particular system, or othermeasurement related to the system. Note that the coupling of the varioussensors to the databus 130 may be direct or indirect. For example, datafrom a particular sensor may be provided to another component, such asdirectly to a microprocessor 150 of the electric vehicle. Subsequently,the microprocessor 150 may provide the information on databus 130. Thedata from the various sensors may be optionally stored in an internalmemory 152 of the electric vehicle 12. In FIG. 4, the memory 152 isillustrated as being coupled to microprocessor 150. However, this may beoptional and the memory 152 can be coupled to databus 130, eitherdirectly or through some other components. In one aspect of the presentinvention, test device 14 monitors information from sensors within theelectric vehicle in order to provide enhanced diagnostics withoutrequiring connection of additional sensors to the vehicle. This isachieved by retrieving data through the databus 130 of the electricvehicle as the various sensors within the vehicle communicateinformation.

In measuring electrical parameters of components, it is often desirableto couple to the electrical component through a four point “Kelvin”connection. In such a configuration, a first pair of connections areused to measure a voltage across the component while a second pair ofconnections are used to carry current. Kelvin connections reduce errorsin the measurements associated with the electrical leads and wiringwhich are used to couple to the component. However, in many electricvehicles, it is extremely difficult to place Kelvin connectors onto thevarious electrical components. Further, even if such connections aremade, they may carry high voltages which may be unsafe for an operator.Therefore, it is often difficult to couple to the electrical systems ofan electric vehicle using traditional Kelvin connection techniques whichhave been associated with the automotive industry.

In one aspect, the present invention provides a “virtual” Kelvinconnection to electrical components of the vehicle. The “virtual” Kelvinconnection is embodied in microprocessor 33 of the test device 14.Microprocessor 33 receives current and voltage information from a pairof sensors, such as current sensor 140A and voltage sensor 142A, whichare coupled to a component of the vehicle such as system A. Using thisinformation, the microprocessor 33 is capable of calculating anelectrical parameter associated with that particular system. Forexample, electrical resistance can be calculated using ohms law asR=V/I. However, other electrical parameters can be calculated such asconductance. Further still, if the electricity through the system has atime varying component, it is possible to determine dynamic parametersof the system such as dynamic resistance or conductance. Complexparameters such as impedance, reactance, etc. of the particular systemcan also be determined. Note that there may be a lag or time delaybetween the two measurements (voltage and current) due to delays in thedatabus 130 or from other sources. Microprocessor 33 can compensate forsuch a lag by determining, or at least approximating, the duration ofthe delay. One technique which can be used is by monitoring a functionor activity within the vehicle, for example, a braking function, whilemonitoring the outputs from the associated current and voltage sensors.Based upon when the current and voltage begin to change relative to oneanother, it is possible to compensate for any delays if the relationshipis known. For example, the voltage and current may be expected to risesimultaneously in some systems. If there is a lag in the voltagemeasurement, for example, the duration of that lag can be measured bymicroprocessor 33 and used to compensate subsequent measurements.Similarly, a particular sensor may have a relatively long response time,or the databus 130 may be of a sufficiently slow data rate thatsufficient band width may not be available to measure or monitor arapidly changing voltage or current. Again, compensation techniques canbe used to at least partially address such a shortcoming, for example,by providing a compensated frequency response profile for a particularsensor.

During operation, microprocessor 33 collects data from a desired system(A-N) of electric vehicle 12 using the associated current sensor 140A-Nand/or voltage sensor 140A-N as desired. The microprocessor 33 can alsouse information collected from other sensors of the electric vehicle,such as sensors A, B and C for use in testing. If a measurement isdesired across multiple systems, it is possible to add or subtract themeasurement currents and voltages to obtain such a measurement dependingupon the configuration of the sensors. As discussed above, the data isretrieved from databus 130 using OBD I/O circuitry 112 coupled to thedatabus 130 through OBD connector 132. In addition to having a userinput/output 110, another optional input/output 160 is illustrated. I/O160 can comprise circuitry for providing data to, or receiving datafrom, another device such as a remote location which collects data ormeasurements, a printer, a remote control or display for use by anoperator, remote sensors, etc. Additionally, other optional sensors 162are shown in test device 14 of FIG. 4. Sensors 162 may comprise othersensors used to perform diagnostics including physical Kelvinconnectors, current and/or voltage sensors, temperature sensors, etc.The user I/O circuitry 110 can be used to provide an interface for anoperator during testing of electric vehicle 12. For example, theoperator can instruct the test device 14 as to which of the systems ofelectric vehicle 12 to test, a selected test to perform, provideinformation regarding electric vehicle 12, etc. The I/O circuitry 110can also be used to provide information to the operator such as theresults of the test, intermediary results, information regarding pasttests, information regarding the electric vehicle or other information.Additionally, if a particular test requires the electric vehicle to beoperated in a particular manner, the user I/O circuitry 110 can provideinstructions to the operator. For example, the particular test beingperformed may require that the electric vehicle be accelerated, or thatthe brake be applied, that the electric vehicle be stopped for a period,or other actions. The instructions to an operator may be in the form of,for example, audible instructions which may be easily implemented whendriving the electric vehicle. Using the data collected from the sensors,microprocessor 33 can diagnose the systems and operation of electricvehicle 12. In one example of the present invention, the information canbe used to perform any type of diagnostics such as those known in theart. Various types of diagnostics include measuring parameters ofsystems of the electric vehicle, monitoring the amount of energyrecovered during an energy regenerative process such as by recoveringenergy during a braking function, determining the maximum amount ofenergy which may be recovered, or the maximum amount of energy which theenergy storage device can accept at any one time during recharging,monitoring the energy storage device as it ages to identify a loss ofthe capacity to store recovered energy or the overall capacity of thestorage device, monitoring the maximum energy which the energy storagedevice is capable of delivering, etc.

For example, one diagnostic technique includes monitoring a parameter ofa cell or block of cells of the battery pack 20 and observing changesover time, for example changes in impedance, conductance, resistance, orother parameters including dynamic parameters. Another examplediagnostic includes comparing parameters measured for a particular cellor block of cells of the battery pack 20 and observing any imbalancesbetween cells or blocks of cells, or other indications that a particularcell or block of cells is not operating in a manner which is similar tothe remaining cells or blocks of cells. This may be through statisticaltechniques such as observing the distribution of measurements of cellsor blocks of cells, etc. Another example diagnostic technique is simplyobserving voltage differences across cells or blocks of cells in thebattery 10.

In another example, the user I/O 110 is used to provide an outputrelated to carbon dioxide emissions of the electric vehicle 12. Forexample, the output can be an indication of the reduction in carbondioxide emissions of the electric vehicle 12 in comparison to a standardvehicle with an internal combustion engine. In a related example, theamount of energy regenerated by electric vehicle 12, for example using aregenerative braking technique, can be monitored using test device 14and an output provided using user I/O 110 which indicates the equivalentamount of carbon dioxide which would have been generated by typicalinternal combustion engine had the energy not been recovered.

In another example configuration, test device 14 can be used to monitoroperation of electric vehicle 12 and collect information related to theefficiency of the electric vehicle 12 under different operatingconditions. This information is then used by device 14 to instruct andoperator through user I/O 110 to operate the electric vehicle 12 in amanner which increases efficiency. For example, if system A shown inFIG. 4 comprises a regenerative braking system, and system B is thebattery pack for the electric vehicle, the test device 14 can monitorthe energy recovered by the regenerative braking system and the amountof energy which the battery pack is capable of storing. Thus, ifmeasurements indicate that the battery pack is only capable of acceptinga maximum of 50 kW, the device 14 can instruct the operator when brakingto attempt to rapidly approach the 50 kW energy recovering level, andmaintain the 50 kW recovery level for an extended period withoutexceeding that level. This will ensure that the maximum amount of energyis recovered during a braking operation. Similar techniques can be usedto instruct the operator during acceleration periods, idling periods,“stop and go” traffic, etc. In a more advanced configuration, the device14 is configured to control operation of the systems in vehicle 12 in amanner which differs from the configuration provided by the controlsystem, for example, implemented in microprocessor 150 of electricvehicle 12. For example, the test device 14 can provide instructions orinformation on databus 130 which allows the charging system or theregeneration system of electric vehicle 12 to charge the battery pack 20to a higher or lower level than that set by the internal control systemof the vehicle. This may be used, for example, to extend the life ofsystems within the vehicle, increase the range of the vehicle, testcertain systems, or for other functions or purposes.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, although storage batteries or a“battery pack” described, as used herein the term electric energystorage device includes a battery or collection of batteries, capacitorsincluding supercapacitors and to ultracapacitors, and other storagedevices. As used herein, electric vehicle includes any type of vehiclewhich uses an electric motor to propel, or assist in propelling, thevehicle. One example electric vehicle is a vehicle with an electricmotor and an electric storage device such as a battery pack or the like.Another example electric vehicle is an electric vehicle withregenerative techniques in which energy is recovered, for example, fromthe braking process. Another example electric vehicle is a hybridvehicle which also includes an internal combustion engine for use insupplementing electric power, and/or charging the electrical energystorage device. Such a hybrid vehicle may optionally includeregenerative systems for energy recovery. As used herein, “operating” anelectric vehicle includes using the vehicle, or systems of the vehicle,and is not limited to driving the vehicle. In one configuration the testis separate from the vehicle and may be selectively coupled to thevehicle or added after manufacture of the vehicle. The “virtual” Kelvinconfiguration calculates a parameter of a system of the vehicle usingtwo or more inputs from sensors which are transmitted over a databus ofthe vehicle.

What is claimed is:
 1. A method of testing an electrical system of anelectric vehicle, comprising: operating the electric vehicle; couplingto a databus of the electric vehicle; monitoring data on the data busand retrieving information related to current flowing into the system ofthe electric vehicle during the step of operating; monitoring data onthe databus and retrieving information related to a voltage of thesystem during the step of operating; and diagnosing the electric vehiclebased upon the monitored current and the monitored voltage.
 2. Themethod of claim 1 including instructing an operator regarding operationof the electric vehicle.
 3. The method of claim 1 wherein diagnosingincludes comparing monitored current and monitored voltage or functionof the monitored current and monitored voltage with nominal values. 4.The method of claim 1 including wirelessly communicating.
 5. The methodof claim 1 wherein the databus comprises an OBD databus.
 6. The methodof claim 1 wherein the system comprises a battery pack of the vehicle.7. The method of claim 6 including monitoring a second system of thevehicle.
 8. The method of claim 7 wherein the second system comprises aregenerative braking system.
 9. The method of claim 8 wherein diagnosingcomprises monitoring energy output from the regenerative braking systemand monitoring energy input into the battery pack.
 10. The method ofclaim 9 wherein the diagnosing further comprises determining efficiencyof the transfer of energy recovered from the regenerative braking systemand stored in the battery pack.
 11. The method of claim 1 wherein thesystem comprises a block of cells of a battery pack of the electricvehicle.
 12. The method of claim 11 including monitoring a second blockof cells of the battery pack.
 13. The method of claim 12 wherein thediagnosing comprises comparing a parameter of the first block of cellswith a parameter of the second block of cells.
 14. The method of claim 1wherein the diagnosing comprises measuring a parameter of the system.15. The method of claim 14 wherein the parameter comprises a dynamicparameter.
 16. The method of claim 1 including providing an output to anoperator of the electric vehicle.
 17. The method of claim 16 wherein theoutput comprises instructions related to operation of the vehicle foruse in performing the step of diagnosing.
 18. The method of claim 1wherein the electric vehicle comprises a hybrid vehicle.
 19. The methodof claim 18 wherein the system comprises an electric generator coupledto an internal combustion engine of the electric vehicle.
 20. The methodof claim 19 including monitoring a second system of the electricvehicle, wherein the second system comprises a battery pack and the stepof diagnosing comprises determining efficiency of storage of energy fromthe generator by the battery pack.
 21. The method of claim 1 wherein thediagnosing includes compensating for a delay between retrievinginformation related to current flowing into the system and retrievinginformation related to a voltage of the system.
 22. The method of claim1 including placing information onto the databus which affects operationof the electric vehicle.
 23. The method of claim 1 including placinginformation onto the databus which affects operation of a system of theelectric vehicle.
 24. The method of claim 1 including providing anoutput to an operator of the vehicle to instruct the operator to operatethe vehicle in a manner to increase energy efficiency.
 25. An apparatusfor testing an electric vehicle, comprising: a databus connectorconfigured to connect to a databus of the electric vehicle; amicroprocessor configured to: retrieve voltage information from thedatabus of the electric vehicle provided by a voltage sensor coupled toa system of the electric vehicle; retrieve current information from thedatabus of the electric vehicle provided by a voltage sensor coupled tothe system of the electric vehicle; and diagnose the operation of thevehicle based upon the retrieved current information and the retrievedvoltage information.
 26. The apparatus of claim 25 wherein themicroprocessor compares monitored current and monitored voltage or afunction of monitored voltage and monitored current, with nominalvalues.
 27. The apparatus of claim 25 wherein the databus comprises anOBD databus.
 28. The apparatus of claim 25 wherein the system comprisesa battery pack of the vehicle.
 29. The apparatus of claim 25 wherein themicroprocessor monitors a second system of the vehicle.
 30. Theapparatus of claim 29 wherein the second system comprises a regenerativebraking system.
 31. The apparatus of claim 30 wherein the microprocessormonitors energy output from the regenerative braking system and monitorsenergy input into the battery pack.
 32. The apparatus of claim 31wherein the microprocessor further determines efficiency of the transferof energy recovered from the regenerative braking system and stored inthe battery pack.
 33. The apparatus of claim 25 wherein the systemcomprises a block of cells of a battery pack of the electric vehicle.34. The apparatus of claim 33 wherein the microprocessor monitors asecond block of cells of the battery pack.
 35. The apparatus of claim 34wherein the microprocessor compares a parameter of the first block ofcells with a parameter of the second block of cells.
 36. The apparatusof claim 25 wherein the microprocessor measures a parameter of thesystem.
 37. The apparatus of claim 36 wherein the parameter comprises adynamic parameter.
 38. The apparatus of claim 25 including an outputprovided to an operator of the electric vehicle.
 39. The apparatus ofclaim 38 wherein the output comprises instructions related to operationof the vehicle for use in performing the step of diagnosing.
 40. Theapparatus of claim 25 wherein the electric vehicle comprises a hybridvehicle.
 41. The apparatus of claim 25 wherein the system comprises anelectric generator coupled to an internal combustion engine of theelectric vehicle.
 42. The apparatus of claim 41 wherein themicroprocessor monitors a second system of the electric vehicle, whereinthe second system comprises a battery pack and the microprocessordetermines efficiency of storage of energy from the generator by thebattery pack.
 43. The apparatus of claim 25 wherein the microprocessorcompensates for a delay between retrieving information related tocurrent flowing into the system and retrieving information related to avoltage of the system.
 44. The apparatus of claim 25 wherein themicroprocessor is configured to place information onto the databus whichaffects operation of the electric vehicle.